diff --git a/src/main.cpp b/src/main.cpp
index 2b67f14..f487152 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -17,10 +17,12 @@
 uint8_t ReadCoilRegister[] = {0, 1, 2};
 uint8_t output_pins[] = {0,1};
 uint8_t ReadInputRegister[] = {0,1,2,3,4,5,6,7};
+uint8_t WriteSingleRegister[] = {0};
 
 uint8_t ReadCoilRegister_size = sizeof(ReadCoilRegister) / sizeof(ReadCoilRegister[0]);
 uint8_t output_pins_size = sizeof(output_pins) / sizeof(output_pins[0]);
 uint8_t ReadInputRegister_size = sizeof(ReadInputRegister) / sizeof(ReadInputRegister[0]);
+uint8_t WriteSingleRegister_size = sizeof(WriteSingleRegister) / sizeof(WriteSingleRegister[0]);
 
 int ValueInputOne = 0;